No more so than any other agricultural activity and, in some situations, probably less.

Outside the boundaries of the cultivated area, herbicide-tolerant crops have no growth advantage because there is no herbicide being sprayed there. For them, herbicide resistance is a genetic burden and, without the farmer’s tender loving care, they will tend to die out in the competition for survival.

Resistance to insect, fungal and viral attack would be an advantage where those pests were present
But remember that many plants already contain their own indigenous pesticides with which they resist attack; in some cases, up one quarter of the plant’s activity is to protect itself in this way, so in most cases adding an extra factor makes little difference.

Food plants have, during the course of agricultural breeding, lost some of those resistances as crops were bred primarily for productivity, taste and nutritional quality. Putting one in will again not have much if any effect outside the planted area.

It is interesting to note that when plants are protected from attack by being sprayed with “chemical” pesticides, they tend to have less of their own. Conversely, when they are under more stress (as, for example, in some forms of organic farming, in which pest control is poor), the plants make more of their own internal chemicals.

More than 90% (perhaps more than 99%) of all the pesticides we consume in our food are inside the plants, not residues left on the outside as a result of spraying. It could be the case that eating organic products actually delivers more pesticide to the person doing the eating. That is a matter of choice. Those pesticides inside the plants may be regarded as more “natural” but some “natural chemicals” are amongst the most poisonous substances known.


  questions & answers
39. Do GM crops affect diversity in the countryside?